Existing water pump pliers have the common characteristic of jaws offset at an angle to the pliers handles and a pivot post, in the form of a bolt or rivet, mounted in an area rearward of the jaw on one of the handles and projecting through an elongate slot provided in the other handle. Such pliers incorporate means for enabling selective spacing of the distance between the jaws, which may take the form of spaced apart ridges or teeth provided along an inside long edge of the slot and adapted for incremental selective binding engagement with the pivot post. Another known way of providing distance adjustment between the jaws of such pliers is to provide spaced apart arcuate ridges on the facing surfaces of the slot for engagement by the pivot post. All such tools require two-handed operation to adjust the jaw spacing to the size of a workpiece to be gripped between the jaws. This adjustment involves pulling the handles apart to permit the pivot post to slide along the slot to move the movable one of the jaws to a position that provides a jaw spacing approximating to the size of the workpiece that is to be gripped.